KR20120126339A - Method of fabrication for nano particle complex catalyst by plasma ion implantation and Device for the method - Google Patents

Abstract

PURPOSE: A manufacturing method of nanoparticle complex catalyst by plasma ion implantation and a manufacturing method of the same are provided to increase the surface area of an catalyst due to the small size of catalytic components. CONSTITUTION: A manufacturing method of nanoparticle complex catalyst by plasma ion implantation includes the following steps: plasma ions of solid elements functioning as catalytic components are generated in a vacuum bath; and ionized catalytic components are injected into the surface of a porous carrier. When pulse is applied to a deposition source under low average power, pulse direct current power is applied to the deposition source to generate the plasma ions of the solid elements.

Description

Method of fabrication for nano particle complex catalyst by plasma ion implantation and Device for the method

The present invention provides a nanoparticle composite catalyst including nanoparticle catalyst particles by a method of supporting a catalyst component of a solid element on a porous carrier, which generates and accelerates plasma ions of the solid element to the porous carrier. It relates to a method for producing a catalyst, characterized in that using a method of injecting and to an apparatus used in the method.

A commonly used method for preparing a catalyst by carrying catalyst active ingredient particles (hereinafter referred to as 'catalyst component' or 'catalyst particle') on a porous carrier is to immerse the porous carrier in a solution in which the catalyst component is dissolved. It is a method to infiltrate the porous structure with the solution or to immerse the porous carrier in the slurry in which the catalyst component is dispersed so that the catalyst particles enter the porous structure. Usually this is called 'impregnation method'.

That is, by impregnating the porous carrier in an environment in which the catalyst component is dissolved or dispersed for a predetermined time, the solution containing the catalyst particles or the catalyst component penetrates into the porous structure of the porous carrier, and then the solvent component is heated by heating. If removed, a catalyst having a catalyst component supported on every corner of the porous structure is produced. In this way, a porous structure in which fine catalyst particles are dispersed can be produced.

By the way, the catalyst produced by this impregnation method has a small catalyst particle size of several nm, but a catalyst particle large in several tens of nm is also obtained, resulting in a decrease in catalyst characteristics due to an increase in the average particle size.

In addition, much larger amounts of catalyst particles have to be prepared in the slurry or solution phase in order to support a certain amount of the catalyst component on the carrier, which is commonly used as a catalyst component and is an expensive precious metal. Therefore, when the catalyst is produced by the impregnation method, expensive catalyst components may be wasted. For example, in the catalytically active plate used in the microreactor, the production of the catalytically active plate in which the carrier is present only on one side of the metal plate is also performed. In this case, the catalyst component should be supported only on the carrier. However, in the impregnation method, there is a disadvantage that the catalyst component remains on the surface of the metal plate without the carrier, which is undesirable in terms of cost required for preparing the catalyst.

On the other hand, there is an ion implantation (Iron implantation) method to modify the surface of the material. This is a technique of accelerating ions to high energies of tens to hundreds of keV and incident on the surface of a metallic material. This ion implantation technology can form a modified layer up to several thousand micrometers from the surface of the material, and form a gentle composition change layer so that peeling phenomenon due to heterogeneity of the material as in coating does not occur, and is a high energy process. It is almost thermodynamically limited, and because it is a room temperature process, there is an advantage that there is no change in size or deterioration due to heat of a sample.

In addition, the ion implantation technology is not significantly affected by the roughness of the surface, and furthermore, it is easy to control the type, thickness, and degree of modification of the modified layer by adjusting the type, energy, and amount of implanted ions.

However, the ion implantation technology has been developed for the purpose of doping impurities into a semiconductor wafer, which is a planar sample, and there are limitations in terms of apparatuses for use for other purposes. That is, when the ion is extracted from the ion source and accelerated to enter the sample in the form of an ion beam, the ion beam should be shaken for uniform ion implantation. In addition, the method of implanting ions in the form of an ion beam is a three-way rotation of a sample for implanting ions into three-dimensional objects such as molds, tools, and mechanical component parts due to the principle constraint of line-of-sight implantation. And the necessity of masking to prevent sputtering due to oblique incident ions.

In order to overcome the shortcomings of the ion beam ion implantation technology, plasma ion implantation technology using plasma and high voltage pulses (U.S. Patent 4764394, Republic of Korea Patent 137704, European Patent 480688, Canadian Patent 2052080, United States Patent 5126163) This has been proposed. This technique enables uniform and fast ion implantation into a large area three-dimensional sample, and does not require an ion beam dispersing device or the like.

However, most of the plasma ion implantation techniques that have been proposed up to now are possible only in the gaseous state such as nitrogen, oxygen, irgon, and methane, and plasma ion implantation of elements existing in the solid state is impossible. However, although some prior arts (US Pat. No. 5,777,438, US Pat. No. 5,126,163) disclose a plasma ion implantation technique of a solid element using a pulsed cathode arc, a large sized macro particle (Droplet) due to an arc when using a pulsed cathode arc plasma is used. ) Is generated and deposited on the surface of the ion implantation sample, there is a disadvantage that must use a filter using a magnetic field to prevent this.

An object of the present invention is to provide a method for injecting plasma ions of a solid element in supporting the catalyst component of the solid element on a porous carrier. From this, the present invention is to provide a method capable of efficiently supporting the catalyst component of the solid element on the porous carrier. That is, the present invention provides a method for producing a catalyst of a solid element which allows the performance of the desired catalyst activity to be achieved while using a small amount of catalyst components as compared to conventional impregnation methods.

In addition, the present invention is to provide a device for producing a nanoparticle composite catalyst that can be carried out the above method.

The present invention generates plasma ions of a solid element used as a catalyst component in a vacuum chamber maintained in a vacuum state, and nanoparticles are accelerated and injected into the porous carrier surface by ionizing the catalyst component ionized from the generated plasma ions. It provides a method for producing a particle composite catalyst.

Preferably, the solid element plasma ions are generated by applying a pulsed direct current power that applies a high power at the moment when a pulse is applied to the deposition source while maintaining a low average power.

Preferably, the pulsed DC power has a density of 10 W / cm ² ? 10 kw / cm ² , 1 Hz? 10 kHz frequency and 10 usec? It has a pulse width of 1 msec.

Preferably, a high voltage pulse synchronized with the pulsed direct current power is applied to the porous carrier to accelerate solid element plasma ions to the porous carrier side.

Preferably, the high voltage pulse is 1 Hz? 10 kHz frequency, 1 usec? Pulse width of 200 usec and -1 kv? It has a negative pulse high voltage of -100 kV.

Preferably, the vacuum chamber is 0.5 mTorr? The plasma generating gas is injected at a pressure of 5 mTorr.

Preferably, the porous carrier is Si-O, Sn-O, Al-O, Cr-O, Mo-O, Ti-O, Zr-O, Mg-O, WO, VO, Sb-O, RE (rare earth) : It is 1 or more types chosen from the group which consists of an oxide of Sr, Y, a lanthanum group) -O system.

Preferably, the solid element is at least one member selected from the group consisting of Au, Ag, Cu, Co, Ni, Pt, Pd and Rh.

Preferably, plasma is further introduced into the vacuum chamber.

Preferably, the porous carrier is a carrier layer having a thickness of 1-100 μm is formed on a metal or ceramic substrate.

In addition, the present invention is a vacuum chamber inside which is maintained in a vacuum state; A deposition source for releasing ions of a solid element into the vacuum chamber by a pulsed direct current power that applies a high power at the time when a pulse is applied while maintaining a low average power, and is disposed inside the vacuum chamber opposite to the deposition source; Provided is an apparatus for preparing a nanoparticle composite catalyst comprising a porous carrier into which ions of a solid element are injected by a high voltage pulse synchronized to a pulsed direct current power.

Preferably, a plasma generating gas for injecting ions of a solid element into a plasma state is injected into the vacuum chamber.

Preferably, plasma is further introduced into the vacuum chamber.

According to the present invention, a small amount of the solid element catalyst component can be efficiently supported on the porous carrier.

In addition, the catalyst prepared according to the present invention does not cause a phenomenon that the particles of the catalyst component supported on the carrier are agglomerated or detached from the carrier even when exposed to a high temperature and high humidity environment, and thus the catalyst performance does not deteriorate and the catalyst does not deteriorate. It has the advantage of long life.

In addition, the catalyst produced by the present invention is advantageous in that the particles of the catalyst component are small and the surface area of the catalytic activity is increased.

1 is a view showing the configuration of a device for injecting solid element plasma ions into the porous carrier of the present invention.
2 is a TEM photograph of the surface of the catalyst prepared in Example.
3 is a TEM photograph of the surface of the catalyst prepared in Comparative Example.
Figure 4 shows the hydrogen gas generation rate with temperature in the hydrogen gas generation reaction through the DME reforming.

The present invention relates to a method for preparing a catalyst in which a catalyst component of nanoparticles is supported in a porous carrier by supporting a solid element used as a catalyst component on the surface of the porous carrier. To distribute the active catalyst uniformly to nanoparticle size. In the case of the impregnation method, since the catalyst particle size exists in the range of several tens to several tens of nm, it is intended to uniformly disperse the catalyst particles in several nm size by using the ion implantation method.

In addition, the impregnation method inevitably entails a step of dipping the catalyst carrier in the liquid phase, so that a post process of evaporating and removing the liquid phase is necessary. At this time, the use of the noble metal is increased by the phenomenon in which the noble metal catalyst is coated on the unnecessary portion. On the other hand, since the ion implantation method is a dry process, the introduction of the evaporation removal process is unnecessary, and there is an advantage that the catalyst component can be supported only on the necessary carrier.

Specifically, the present invention generates plasma ions of a solid element used as a catalyst component in a vacuum chamber maintained in a vacuum state, and accelerates and injects ionized catalyst components from the generated plasma ions onto the surface of the porous carrier. It provides a method for producing a nanoparticle composite catalyst.

In order to generate plasma ions of a solid element in the vacuum chamber, a deposition source capable of sputtering a solid element such as a magnetron is used. Power must be applied to the deposition source to sputter the solid element. At this time, the power applied to the deposition source uses a direct current of the pulse form that can be applied a high power at the moment the pulse is applied while maintaining a low average power.

When pulsed direct current power is applied to the deposition source, the deposition source is momentarily turned on, and solid elements are sputtered therefrom and discharged into the vacuum chamber. The solid element ions are then brought into a plasma state by the plasma generating gas present in the vacuum chamber at a high density. In order to inject the solid element ions in the plasma state into the porous carrier, the porous carrier is disposed opposite the deposition source, and a high voltage pulse is applied. That is, effective ion implantation can be achieved by causing the solid element ions in the plasma state to be accelerated toward the porous carrier by the high voltage pulse applied to the porous carrier.

Preferably, the pulsed direct current power applied to the deposition source to cause sputtering from the solid element used as the catalyst component has a density of 10 W / cm ² ? It has a value of 10 kw / cm ² , a frequency of 1 Hz to 10 kHz, and 10 usec? Use a pulse width of 1 msec. Further, the high voltage pulse applied to accelerate the solid element ions toward the porous carrier has a frequency equal to 1 Hz ?, which is the same frequency as the pulsed DC power applied to the deposition source. Synchronized at 10 kHz, the pulse width is 1 usec? 200 usec, negative pulse high voltage use -1 kv --100 kV.

The solid element used as the catalyst component in the present invention is at least one selected from the group consisting of Au, Ag, Cu, Co, Ni, Pt, Pd and Rh. By targeting the solid element, the deposition source is operated in pulsed mode rather than in continuous operation. This maintains a low average power so that there is no problem with cooling the deposition source, while allowing very high power to be generated at the moment of application of the pulse to generate a high density of solid element ions on the surface of the deposition source. This is to increase the ionization rate of the solid element.

When a large amount of solid element ions generated in this manner is released into the vacuum chamber, the plasma is generated by the plasma generating gas present in the vacuum chamber. At this time, as the plasma generating gas filled in the vacuum chamber, argon, nitrogen, oxygen, methane, carbon monoxide, carbon dioxide, ammonia, acetylene, benzene gas, and a mixed gas thereof may be used. In addition, the pressure of these gases is 0.5 mTorr? Adjust to 5 mTorr. If the pressure inside the vacuum chamber is lower than 0.5 mTorr, it is difficult to generate plasma, whereas if the pressure is higher than 5 mTorr, the energy loss of the solid element ions is severe due to frequent collision of the solid element ions and gas particles. .

In order to effectively inject the solid element ions in the plasma state thus generated into the porous carrier disposed at a position opposite to the deposition source, a high voltage pulse of negative charge is applied to the porous carrier. When a negative high-voltage pulse is applied to the porous carrier, ions are extracted from the solid element plasma generated from the deposition source, accelerated toward the porous carrier, and ion implantation is effectively performed.

In addition, the high voltage pulse should be synchronized with the pulsed DC voltage applied to the deposition source. This is because the solid element sputtered from the deposition source is ionized in the vacuum chamber and accelerated toward the porous carrier by the high voltage pulse applied to the porous carrier at the moment when the deposition source is pulsed on by the pulsed direct current voltage applied to the porous carrier. This is because it must be ion implanted. The high voltage pulse is preferably a voltage between -1 kV and -100 kV.

In the present invention, the porous carrier is Si-O, Sn-O, Al-O, Cr-O, Mo-O, Ti-O, Zr-O, Mg-O, WO, VO, Sb-O, RE (rare earth: It may be selected from the group consisting of Sr, Y, and Lanthanum) -O-based oxides.

Such a porous carrier is preferably used while placed on a mount made of a conductive material capable of applying a high voltage pulse. The mounting bar may be used without limitation as long as it is a conductive material such as copper or stainless steel.

In addition, the porous carrier is present in the form of a coating on a metal substrate or a ceramic substrate, the thickness of 1-100 μm may be used.

A plasma may be additionally introduced into the vacuum chamber from the outside of the plasma generating gas. Plasma introduced from the outside into the vacuum chamber not only increases the ionization rate of the solid element emitted from the deposition source, but also enables the deposition source to operate at a pressure lower than the operating pressure, thereby preventing collision with gas particles during ion implantation. It can be minimized.

In order to introduce the plasma, RF power may be applied to the RF antenna to generate an inductively coupled plasma of a plasma generating gas that is already present in the vacuum chamber, to use filament discharge, or to use microwave.

In the present invention, the size of the solid element immediately after injection into the porous carrier is several nm. Therefore, the catalyst prepared in the present invention is a nanoparticle composite catalyst in which the catalyst component is present at the nano level. This is a much smaller size than the catalyst component particles present in the impregnation method in the range of several tens to several tens of nm, and the catalyst prepared by the present invention has the effect of widening the surface area of the catalytically active component.

In addition, the ions of the solid element injected into the carrier by the method of the present invention have stronger interaction with the surface of the porous carrier than in the case of the impregnation method. Therefore, the sintering phenomenon is less likely to occur even when exposed to a high temperature and high pressure catalyst use environment, and thus the catalyst performance is not easily deteriorated even by prolonged use.

On the other hand, as an embodiment of the device capable of implementing the catalyst production method of the present invention, as shown in Figure 1 is a patent pending "solid element plasma ion implantation device" (Korean Patent Application No. 10-2009-0002986 Can be used. That is, a solid element, which is a catalyst component, is mounted as a target of the magnetron to operate in a pulse mode using a pulsed direct current power source, and a high voltage pulse synchronized with the same is applied to a porous carrier used as a sample, thereby obtaining ions of the solid element generated from the magnetron. It can accelerate ion implantation on the surface of the porous carrier. However, the apparatus capable of realizing the method of the present invention is not limited to the apparatus disclosed in the above patent, but includes a vacuum chamber in which the inside is kept in a vacuum state; A deposition source for releasing ions of a solid element into the vacuum chamber by a pulsed direct current power that applies a high power at the time when a pulse is applied while maintaining a low average power, and is disposed inside the vacuum chamber opposite to the deposition source; It can be used without limitation as long as it includes a porous carrier into which the ions of the solid element are injected by the high voltage pulse synchronized to the pulsed direct current power.

In addition, in the apparatus, argon, nitrogen, oxygen, methane, carbon monoxide, carbon dioxide, ammonia, acetylene, benzene gas, and a mixed gas thereof are mixed in a vacuum chamber to make solid elements into a plasma state. It can be injected at a pressure of 5 mTorr, and the RF antenna generates an inductively coupled plasma of the plasma generating gas already present in the vacuum chamber in order to increase the ionization rate of the solid element and to effectively inject the solid element into the porous carrier. The external plasma may be further introduced using the filament discharge, the microwave, or the microwave.

In addition, ions are injected by applying a high voltage pulse in a state where the porous carrier is placed thereon using a mount of conductive material to apply a high voltage pulse to the porous carrier.

Hereinafter, the invention will be described in detail by way of examples. However, since this is to facilitate the understanding of the invention, the present invention should not be considered to be limited thereto.

Example

Platinum (Pt) was used as a target of the magnetron deposition source as a solid element. As the Pt target, one having a diameter of 75 mm and a thickness of 1 mm was used. As a porous carrier for ion implantation, porous γ-Alumina (thickness 26 μm) prepared through anodizing was used. A porous gamma alumina layer was formed on one side of an Al plate having a length of 4 cm and a width of 2 cm by anodization.

After mounting the porous alumina carrier layer on the conductive sample bed, the vacuum chamber was evacuated to a vacuum of 5 × 10 ⁻⁶ Torr, and argon gas was introduced to maintain an argon pressure of 2 mTorr in the vacuum chamber. Subsequently, an argon plasma was generated by applying RF power of 13.56 MHz and 200 Watt to the antenna for plasma generation, and the magnetron deposition source was operated by applying pulsed DC power to the magnetron deposition source. The applied pulse DC voltage was -1.1 kV and the pulse current was 10 A, and the pulse power of about 220 W / cm <^2> was used. In addition, the frequency of pulse DC power was 100 Hz, and the pulse width was 200 usec. The average power was 220 W so that there was no problem in cooling the magnetron deposition source.

The magnetron deposition source was operated by the above method, and the plasma ion implantation process was performed for 30 minutes by applying a negative high voltage pulse to the alumina carrier layer. The high voltage pulse value used in the experiment was -60 kV, 40 usec, and the frequency was synchronized to 100 Hz, which is the same as the magnetron deposition source. In addition, after a pulse direct current for a magnetron deposition source of 200 usec was applied, a high voltage pulse of 40 usec was applied to the alumina carrier layer after about 100 usec, so that plasma ion implantation was performed at a sufficiently high ion density of plasma. .

Comparative example

Pt particles were supported by the impregnation method on the same porous alumina carrier layer as in Example. To this end, Potassium Hexachloroplatinate (4) (K ₂ PtCl ₆ ) was dissolved in distilled water to prepare a 0.50wt% Pt particle solution. The water was removed by immersing the porous alumina carrier layer therein and taking out and heating at 500 ° C. for 3 hours.

Catalyst Characterization

[Comparison of Catalyst Particle Size Supported on Carrier]

In order to determine the dispersion and particle size of the Pt particles present on the surfaces of the catalysts prepared in Examples and Comparative Examples, the cut surfaces of the catalysts were observed by TEM.

2 is prepared in the Example, and FIG. 3 is prepared in the Comparative Example.

In the left photograph of FIG. 2, the ion-implanted Pt layer was observed at about 50-100 nm, and in the enlarged image at the right, the darker and rounder ones were Pt particles, having a size of 2-3 nm. In contrast, in FIG. 3, black dots are distributed as Pt particles in the size range of several to several tens of nm. That is, the method of the present invention shows that the solid element particles of a smaller size than the impregnation method can be supported on the carrier.

[Catalyst Performance Evaluation]

In order to evaluate the performance of the catalysts prepared in Examples and Comparative Examples, a hydrogen gas evolution reaction through DME reforming was performed. [Pt / [gamma] -Alumina / Al plate] composed on one side of the Al plate having a length of 4 cm and a width of 2 cm was used as the catalytically active plate. The reformers were configured to place two active plates facing each other and to flow the DME gas therebetween. The fuel (gas phase) in the 5 ml / min, space velocity (GHSV) 2,000h ^- was fed to ^one. DME: O ₂ : N ₂ = 5cc: 6cc: 20cc was maintained and supplied.

 Partial oxidation reforming of the DME in the temperature range of 200 ° C. to 500 ° C. is shown in FIG. 4. As shown in FIG. 4, the hydrogen gas generation rate with temperature was about the same in both catalysts.

After the performance evaluation, the amount of Pt actually contained in each catalyst was measured by the ICP method. As a result, it was 0.41 wt% for the catalyst prepared in the example, and 0.58 wt% for the catalyst prepared in the comparative example. That is, the amount of the actual catalyst component in the catalysts of the Examples and Comparative Examples showing the same catalytic performance was found to be about 30% less than that of the catalyst prepared by the impregnation method.

From this it can be seen that when using the method of the present invention to achieve the same catalyst performance, the amount of catalyst components used can be reduced compared to the conventional impregnation method.

Claims (13)

Nanoparticle composite catalyst, characterized in that for generating plasma ions of a solid element used as a catalyst component in the vacuum chamber maintained in a vacuum state, and accelerated injection of the catalyst component ionized from the generated plasma ions to the porous carrier surface Manufacturing method. In claim 1,
The solid element plasma ion is produced by applying a pulsed direct current power to apply a high power at the moment the pulse is applied while maintaining a low average power to the deposition source. The method of claim 2,
The pulsed DC power has a density of 10 W / cm ² ? 10 kw / cm ² , 1 Hz? 10 kHz frequency and 10 usec? Method of producing a nanoparticle composite catalyst characterized in that it has a pulse width of 1 msec. In claim 2,
And a high voltage pulse synchronized with the pulsed direct current power is applied to the porous carrier to accelerate solid element plasma ions toward the porous carrier. 5. The method of claim 4,
The high voltage pulse is 1 Hz? 10 kHz frequency, 1 usec? Pulse width of 200 usec and -1 kv? Method for producing a nanoparticle composite catalyst characterized in that it has a negative pulse high voltage of -100 kV. The method of claim 1,
0.5 mTorr? Method for producing a nanoparticle composite catalyst, characterized in that the plasma generating gas is injected at a pressure of 5 mTorr. In claim 1,
The porous carrier is Si-O, Sn-O, Al-O, Cr-O, Mo-O, Ti-O, Zr-O, Mg-O, WO, VO, Sb-O, RE (rare earth: Sr, Method for producing a nanoparticle composite catalyst, characterized in that at least one selected from the group consisting of Y, lanthanum group) -O-based oxide. In claim 1,
The solid element is a method for producing a nanoparticle composite catalyst, characterized in that at least one selected from the group consisting of Au, Ag, Cu, Co, Ni, Pt, Pd and Rh. In claim 1,
Method of producing a nanoparticle composite catalyst, characterized in that the plasma is further introduced into the vacuum chamber. In claim 1,
The porous carrier is a method for producing a nanoparticle composite catalyst, characterized in that the carrier layer having a thickness of 1-100 μm is formed on a metal or ceramic substrate. A vacuum chamber in which the inside is kept in a vacuum state;
A deposition source for releasing ions of a solid element into the vacuum chamber by a pulsed direct current power applying a high power at the time when a pulse is applied while maintaining a low average power; and
And a porous carrier disposed inside the vacuum chamber opposite the deposition source and into which ions of a solid element are implanted by a high voltage pulse synchronized to the pulsed direct current power. 12. The method of claim 11,
And a plasma generating gas for injecting ions of a solid element into a plasma state is injected into the vacuum chamber. The method of claim 12,
An apparatus for producing a nanoparticle composite catalyst, wherein a plasma is further introduced into the vacuum chamber.

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